The goal of this project is to describe the mechanisms regulating protein degradation in anoxic, hypoxic and ischemic hearts. Factors accounting for inhibition of protein degradation in energy-poor hearts will be explored, including hormones, rates of coronary flow, accumulation of metabolites such as lactate and changes in intracellular pH. Latency of lysosomal enzymes will be measured in homogenates of these hearts. Reversibility of any changes that occur will be investigated. Effects of these conditons on the turnover of whole heart proteins will be compared to those on the turnover of a specific heart protein. Attempts will be made to isolate heart lysosomes. Factors controlling digestion of native and denatured proteins and latency of activity of lysosomal enzymes will be investigated to clarify the role of lysosomes in degradation of myocardial proteins. BIBLIOGRAPHIC REFERENCES: Rannels, D. E., R. Kao and H. E. Morgan. Protein synthesis and degradation during ischemia. Richards Symposium of the Philadelphia Physiological Society, in press (1977). Morgan, H. E.,D. E. Rannels and E. E. McKee. Protein metabolism of the heart. In Handbook of Physiology, Circulation (R. Berne, ed.), in press (1977).